import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

/**
 * @author: gao
 * @create-date: 2025/5/31 19:59
 */

public class Main {
    public static boolean hasDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<>();
        for (int i : nums) {
            if (set.contains(i)) {
                return true;
            } else {
                set.add(i);
            }
        }
        return false;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.nextLine();
        String[] strNum = s.split(" ");
        int[] nums = new int[strNum.length];
        for (int i = 0; i < strNum.length; i++) {
            nums[i] = Integer.parseInt(strNum[i]);
        }
        if (hasDuplicate(nums)) {
            System.out.println("yes");
        } else {
            System.out.println("no");
        }
    }
}
